1. Field of the Invention
The invention relates to a twist drill for drilling having a replaceable drill tip. This invention further relates to a replaceable drill tip for use in a twist drill
Additionally, this invention relates to a drill bit with a replaceable drill bit.
2. Background Information
The modern metalworking trade primarily uses twist drills to make borings. Depending on the application, these twist drills can differ in terms of their cutting material and geometry. The cutting material traditionally used is increasingly being replaced by different types of cutting material that have a significantly higher resistance to abrasion. For large drilling tools, however, a drill made entirely of such abrasion-resistant materials is generally too expensive, and is not economical in spite of its excellent cutting performance. Alternatives are twist drills in which a drill tip made of abrasion-resistant materials is permanently attached to a carrier tool which is generally made of cheaper, more traditional materials. The disadvantage of these tools, however, is that they can be repointed only to a restricted extent. As soon as the short cutting portion made of abrasion-resistant materials has been used up, the entire tool has to be scrapped.
To reduce overall costs and reduce or eliminate waste of material, it is advantageous to construct a drill with a replaceable cutting tip, as discussed herein. Replaceable cutting tips permit a user to replace the cutting tip when the cutting tip is worn down without having to replace the entire drill.
On a drill bit of this type, a cutting head is detachably fixed to a drill shaft. German Patent No. 196 05 157 A1 describes a drilling tool of the prior art in which the cutting head projects by means of a stud into a receiving recess on the face of the drill shaft, where it is fixed in position with a screw that is oriented at a right angle to the longitudinal axis of the drill. On a drilling tool of the prior art described in WO 98/53943, the drilling head is fixed in position in the drill shaft with a force fit that acts in the axial direction and in the direction of rotation of the drill.